Kora documentation new engine

[GoodforGod]

Move Kora documentation to new engine like docusaurus with more feature set

Need to investigate first for best engine possible for desired feature set:

• Separate documentation for different Kora Versions (check Micronaut doc for examples)
• Switch for Java/Kotlin examples in one place, same for Maven/Gradle if needed (check Micronaut doc for examples)
• Different language support (Russian / English)